Silver-metal oxide contact materials

ABSTRACT

A composite electrical contact material consisting of an alloy composed of 6 to 12 weight percent of indium, and 0.5 to 5 weight percent of tin, the balance being silver, said alloy being formed into a strip or electrical contact shape and subjected to internal oxidation. Less than 0.5 weight percent of an element of the iron family is added to the alloy when it contains more than 2.5 weight percent of tin.

United States Patent Shibata Apr. 1, 1975 SILVER-METAL OXIDE CONTACT 2,796,346 6/1957 Stumbock 75/173 A MATERIALS 3.607.244 9/1971 Kabayama 75/173 A 3,694,197 9/1972 Zdanuk et a] 75/173 A [75] Inventor: Akira Shibata, Y0k0hama, .lapan [73] Assignee: Chugai Denki Kogyo Primary Examiner-L. Dewayne Rutledge KabuShiki-Kaisha, Tokyo, Japan Assistant Examiner-E. L. Weise [22] Filed: 14 1973 Attorney, Agent, or Firnz--Shlesinger, Fitzsimmons &

Shelsinger [21] Appl. No.: 442,632

[30] Foreign Application Priority Data [57] ABSTRACT Mar 20. 1973 Japan 48-33133 A COmPOSiI'e electrical Contact material Consisting of July 201 1973 Japan 48-80704 an alloy Composed of 6 to 12 Weight Percent Of dium, and 0.5 to 5 weight percent of tin, the balance 52 11.5. c1 75/173 R being Silver. Said alloy being formed into a strip or [51] Int. Cl. C22c 5/00 electrical Contact Shape and Subjected to internal [58] Field 61 Search 75/173 A dation- Less than 05 weight Percent of an element of the iron family is added to the alloy when it contains 5 References Cited more than 2.5 weight percent of tin.

UNITED STATES PATENTS 5 Claims, N0 Drawings 2,572,662 10/1951 Richardson et a1 75/173 A X Sll.VER-l\lETAL OXIDE CONTACT MATERIALS This invention relates to silver-metal oxide contact materials.

acteristic of the contact material thus obtained were found to be equal or even superior to those of silvercadmium alloy material having comparable composition. It is found that when the weight percentage of tin While silver-cadmium oxides are popular as a com- 5 falls below 0.5 weight the refractoriness ofthe mateposite contact material. practical examples of the rial is adversely affected on account of the lowered contact material consisting of silver and oxides other oxide concentration. It is also found that addition of than cadmium oxides that may be produced by the more than 2.5 weight "/1 of tin retards the progress of method of internal oxidation are rather few. in effect. the internal oxidation and. as in the case ofthe Ag-CdO material consisting of silver and cadmium oxides which alloy, the aforementioned elements. such as those of are internally oxidized has excellent antifusibility and. Ills il'tm amily. hil I dde in r k ilm nlh l for this reason. it is considered an indispensable matemilkb the Structure Uniform rial for producing electrical contacts to be used for in- Th0 CllCht properties of the contact material of dustrial devices especially under medium load operatthis invention 1111 LXhlhlwd especially in 611595 ing conditions. Many other oxides treated in the past in tclll'l'cm'hrcllklng lull-formalCc l5 l This various literature cl-c d i ll pmducing improved anti-weld characteristic of the contact mateelectrical contacts by the internal oxidation process on l'lill lhc Prcscm lm'cmlmi bu ilttl'lhmcd m the very mm occusions Owing to the wcukncss ohscrwd in fact that when the indium oxide has expelled its oxygen Contact resist-met dmpwcid Characteristic, Son-ice life in the silver matrix and has been turned into solid soland other mquil-cmcnts for Clcctricu] comucts ute. its vapor pressure becomes low. and re-oxidization Among these oxides. indium oxides are noticeable mkcs Plucc duc m thC clcvlm-d tcllllwmtul'c Caused y Oncs bchcuusc d u cmmlining as much as 12 are generation. and thus the oxide concentration on the weight pcrccm of indium is internally Oxidimblc amp surface of the material is not lowered as in the case of furthcr bccuusc this all"). h,1S prcfcmncc Our Silva; 2Q Ag-CdO alloy material and contacts made thereof. cadmium alloy from the view point of combatting the i problem of pollution. This alloy. however. has not been EXAMPLE 1 adopted WidCl) reason Of il'lC fOl'lilZlliOll Of llClCLlllll' Thc n ctul unoyg haying [he on posiflons how in structures in the matrix in the course of the internal oxthe following Table l were formed by melting them idation. thereby inhibiting the formation of dispersed into plates clad with silver on their back surfaces. nuclei of oxidized precipitates therein. The addition of These test samples. 0 mm in diameter and 1.5 mm in trace amounts of such elements as Mn. Co. Mg. Zr or thickness, were subjected to an internal oxidation at the metals of iron group into the alloy would work to about 700C and under the pressure of 3 atm of oxya considerable extent for comminuting crystals or regen. The samples. were tested as to their hardness. tarding the growth of coarse crystals. The alloy inter- ASTM wear rate and anti-weld characteristic. The test nally oxidized with the addition of such metallic eleresults are given in said Table l. by which it is conments had. indeed. an improved structure. however. it firmed that the same value of anti-weld characteristic was still inferior to the Ag-CdO alloy of comparable as that of Ag-CdO alloy material having comparable composition in point of anti-weld characteristic and ancomposition could be obtained by addition of().5 to 2.5 tiarc properties. Though it was impossible to deterweight'/( ofSn.and that the stableindium oxides could mine whether the produced indium oxide was either be tained by XidiZing indium with such amount of [11 0. 1110 or ln. ,O because of the low partial pressure Sn. These results clearly show that the Ag-ln alloy maof oxygen penetrated to the alloy. this re lt was terial can be used satisfactorily for Ag-CdO alloy mateagainst our theoretical assumption that the refractory lizll. t ay nothing of valuable effects on combatting properties ofthe indium oxide having the highest oxide thc Pmhlcm of environmental Pollution Table 1 Samples Hardness Wear Amount ting.) Current (A) for the (HRF) on ASTM test occurrence of Welding Ag-Cd 10% 8.0 3.000 Ag-ln 10% 70 10.0 2.000 Ag-Cd l0"/(. Ni 0.2% 45 6.0 2.000 Ag-ln I071. Ni 0.2% 65 8.5 2.000 Ag-Cd 10%. Sn 2%. Co 0.1% 80 8.5 6.000 Ag-ln 10%. Sn 2%. Co 0.17! 80 8.0 6.000

concentration must be better than those of 0.10. T bl 2 The inventor has made a study of components which can be added to a silver-indium alloy for improving the Samplcs Number of Occurrence of Weld refractory property of indium oxides thereof. and has found that the addition of Sn is effective for the pur' pose.

Accordingly. in this invention. indium oxides are precipitated in the silver matrix as compound oxides with Sn with the progress of the internal oxidation. by adding Sn in more than 0.5 weight percent. thus producing the hard contact material dispersed with refractory oxides. The hardness. refractoriness and anti-weld charl) Ag-Cd 15% 4 (I) Ag-ln l2/: 8 (3) Ag-ln ltV/i. Sn 37:. Ni 0.27: (l

times: 100,000, Contact pressure: 400 g.. and Opening force: 600 g. The current in Table l at which welding occurcd on the samples, was measured under the following conditions: Contact pressure: 400 g.. Discharge current: V=l0, Z0. 30. 40, 50. 60. 70. 80, I00. I10. 120, 130. 140. 150. 160. and Peak current: lm=28.6 V(A) EXAMPLE 2 A further comparative test was carried out on the antiweld characteristic of the known silver-cadmium and silverindium oxide alloy materials and the present invention contact material obtained by conducting the internal oxidation with the material consisting of 8 to 12 '71 of indium. 2.6 to of Sn. and less than 0.5 weight '7( of the elements of the iron group. the balance being silver. The result of the test is given in the Table 2 at page 5. The test conditions for the Table 2 are as follows:

Voltage: DC. 200 V, lnitial current: 5.700 A, and

Contact pressure: 200 g.

Occurrence of welding was measured times for five specimens of each test sample. The sample (3) in the Table 2 represents a product of this invention obtained through the internal oxidation of the material of the composition given in said Table, which was 6 mm in diameter and 2 mm in thickness.

What is claimed is:

l. A composite electrical contact material consisting of an alloy composed of 6 to IE weight percent of indium. and 0.5 to 5 weight percent of tin, the balance being silver. said alloy being formed into a desired configuration and subjected to an internal oxidation.

2. A composite electrical contact material as claimed in claim 1. in which the alloy contains less than 0.5 weight percent of element of the iron family.

3. A composite electrical contact material as claimed in claim 2, in which indium is contained in the alloy at 8 to 12 weight percent. and tin is contained at 2.6 to 5 weight percent.

4. A composite electrical contact material as claimed in claim 2, wherein the alloy contains more than 2.5 weight percent of tin.

5. A composite electrical contact material as claimed in claim I. wherein the alloy contains less than 0.5% of nickel.

Patent No Inventor (s) UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION 3,87 l,9 ll Dated April l, l975 Akira Shibata It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the front page of the patent, in paragraph [22],

the filing date should read February 1 1, 197 1 rather Pthan "February 1A, 1973".

"Mar. 20, 1973" should read Mar. 22

In paragraph [30], line 2,

Signed and Scaled this Fifteenth Day Of November I977 [SEAL] Attest:

RUTH C. MASON LUTRELLE F. PARKER Attesting Ojficer Acting Commissioner of Patents and Trademarks 

1. A COMPOSITE ELECTRICAL CONTACT MATERIAL CONSISTING OF AN ALLOY COMPOSED OF 6 TO 12 WEIGHT PERCENT OF INDIUM, AND 0.5 TO 5 WEIGHT PERCENT OF TIN, THE BALANCE BEING SILVER, SAID ALLOY BEING FORMED INTO A DESIRED CONFIGURATION AND SUBJECTED TO AN INTERNAL OXIDATION.
 2. A composite electrical contact material as claimed in claim 1, in which the alloy contains less than 0.5 weight percent of element of the iron family.
 3. A composite electrical contact material as claimed in claim 2, in which indium is contained in the alloy at 8 to 12 weight percent, and tin is contained at 2.6 to 5 weight percent.
 4. A composite electrical contact material as claimed in claim 2, wherein the alloy contains more than 2.5 weight percent of tin.
 5. A composite electrical contact material as claimed in claim 1, wherein the alloy contains less than 0.5% of nickel. 